Multilayer films having one or more tie layers containing a blend of an ethylene/alpha-olefin copolymer and a plastomer and/or an elastomer, are known. Such tie layers are internal film layers which those of skill in the art recognize as being compatible with other compositions, i.e., suitable for direct adhesion to, for example, ionomers and polyethylene homopolymers and copolymers.
Multilayer films with one or more surface layers containing a blend of an ethylene/alpha-olefin copolymer and a plastomer, and/or an elastomer, are also known. However, such films have been used in a manner in which the outer blend-containing sealing layer is sealed to itself, and the package is a high strength, heat-resistant structure which has been used as dunnage bags (which contain air, and are used to stabilize loads during shipping, these films comprising an ethylene/alpha-olefin copolymer having a density of about 0.916 or greater) and for use in the packaging of water softener, i.e., salt pellets.
Ionomers such as metal-neutralized copolymers of an olefin and a carboxylic acid are also known for use in an outer film layer. Ionomers are advantageous in the (outer) sealing layer of a film because they melt at relatively low temperature and produce a relatively strong heat seal. However, ionomers are expensive relative to other polymers typically used in packaging films.
Since ionomer-containing resins are expensive, it would be desirable to use less ionomer, or no ionomer, without sacrificing the advantageous properties provided by ionomers, such as low seal initiation temperature, relatively high seal strength, relatively high hot tack strength, suitability for seals used in cook-in conditions, acceptable for food contact, etc. Furthermore, it would also be desirable to provide a film having a relatively thick layer or layers which undergo melt flow during sealing, so that the resulting seal is capable of sealing through or around surface imperfections, or contamination such as dust, fat, water, the product being packaged, e.g. food, such as meat. Of course, it would also be desirable to provide at low cost this relatively thick region capable of melt flow during sealing, i.e., using compositions which are inexpensive, especially compositions less expensive than ionomer.